Method for transporting sulfur by pipeline



form known in the art as sulfur n,

United States Patent 3,339,985 METHOD FOR TRANSPORTING SULFUR BY PIPELINE Richard L. Every and DArcy A. Shock, Ponca City, Okla., assignors to Continental Oil Company, Ponca City, Okla., a corporation of Delaware N0 Drawing. Filed June 4, 1965, Ser. No. 461,537 10 Claims. (Cl. 302-66) This invention relates to the sulfur. More particularly, the invention relates to the transport of sulfur through a pipeline in the form of solid particles suspended in a pumpable slurry.

It has heretofore been proposed to convey sulfur between locations separated by substantial distances by forming the sulfur in small particles, suspending these particles in a carrier liquid to form a pumpable slurry and forcing the slurry through a pipeline linking the two locations. It has also been proposed to form the solid particles in situ in the slurry by initially introducing molten sulfur to the carrier liquid at a temperature above that at which the sulfur freezes, then lowering the temperature of the liquid mixture during agitation thereof to yield a pumpable slurry containing solid particles of the sulfur. Pipeline transport of the sulfur is used to move the sulfur from mining sites where it is brought to the surface by use of the Frasch process, as well as for transshipment from stockpile locations to refineries or treatment plants. Since sulfur occurs naturally in a crystalline form, the slurries previously prepared for pipeline transport have included sulfur particles of this allotropic form.

A problem which has been encountered in the pipeline transport of sulfur slurries is the propensity of the sulfur to precipitate or plate out on the walls of the pipeline, and particularly, upon the internal elements of valves and fittings. This plating out of the sulfur reduces the operating efficiency of the transport, requires increased maintenance of equipment, and contaminates the pipeline to a degree which presents serious problems if it is desired to use the same pipeline for transporting other materials in a relatively high state of purity.

The present invention provides an improved procedure for transporting sulfur through a pipeline in that the extent to which the sulfur is precipitated or plated out in the pipeline during the movement of the sulfur therethrough is substantially reduced. Broadly described, the method of the invention comprises initially converting at leasta portion of the sulfur from its usual naturally occurring crystalline allotropic form to its amorphous allotropic then comminuting or subdividing the sulfur to provide relatively small particles thereof having an average particle size which, in general, do not exceed inch in diameter. The sulfur particles arethen introduced to a suitable carrier liquid to form a slurry having a sufliciently low 'viscosity that the material can be pumped through a pipeline without difficulty. The carrier liquid is a liquid in which the sulfur particles are insoluble, or at least are not soluble to a degree exceeding 5 Weight percent. After formation of the slurry, it can be pumped through a pipeline over substantial distances without the occurrence of sulfur precipitation or plating out to an unacceptably high degree.

In a specific though non-limiting aspect of the invention, the sulfur ,u. is derived from the reaction of gaseous hydrogen sulfide with liquid sulfur dioxide to yield solid sulfur and Water. The hydrogen sulfide canbe derived from any convenient source, such as natural gas wells, conversion ofelemental sulfur mined by the Frasch process or the like. The solid sulfur which is yielded by the described reaction is, to theextent of at least 50 weight percent, in the amorphous or sulfur ,u. allotropic form.

pipeline transport of 7 Patented Sept. 5, 1967 ICC Because of the high sulfur ,u content, the solid sulfur product of the reaction can be pipelined after comminution and slurrying without separation of the amorphous sulfur from the crystalline form. Alternatively, if a minimum of precipitation and plating out of the sulfur in the pipeline is sought, the amorphous form can be separated from the crystalline form by carbon disulfide extraction of the crystalline sulfur from the carbon disulfide-insolu ble sulfur ,u.

The mechanism which is responsible for the lesser tendency of the sulfur n to be deposited upon surfaces contacted during movement through a pipeline, as compared to the tendency of the crystalline sulfur to be so deposited is not well understood. In any event, We have observed a reduction of well over 50 percent in the amount of sulfur which is precipitated or plated out in the course of pipeline transport of sulfur slurries when the sulfur utilized is in the amorphous form as compared to the crystalline allotropic form. In most instances, the reduction in the amount of sulfur plated and precipitated out in the pipeline is over percent.

From the foregoing description of the invention, it will be apparent that it is an important object of the present invention to provide an improved process for transporting sulfur by pipeline.

A more specific object of the invention is to provide an improved procedure for transporting sulfur containing slurries over substantial distances by pipeline.

An additional object of the present invention is to reduce the maintenance of pipeline equipment which is required in the case of pipelines used for transporting sulfur slurries.

In addition to the foregoing described objects and advantages of the invention, other objects will become apparent from the following detailed description of the invention.

The modus operandi of the present invention is based in our discovery that, for a reason not presently fully understood by us, the amorphous allotropic form of sulfur, termed sulfur n, is not as readily deposited on solid surfaces encountered in pipeline transport as is the crystalline sulfur, which is by far the predominant allotropic form in naturally occurring sulfur. Over a period of time, the sulfur will revert to the crystalline form, but it will remain in its amorphous form for an adequate period oftime for most purposes involving pipeline transport. The reduction in sulfur precipitation occurring in the pipeline varies with the amount of sulfur ,u. in the total solid sulfur transported so that it is desirable to convert as much of the sulfur to be transported to this allotropic form as is possible. The naturally occurring sulfur generally contains less than about 1 Weight percent of the amorphous form of the element.

Any suitable method of converting the crystalline sulfur to the amorphous form can be employed, but we prefer to utilize a process in which the sulfur is initially converted to hydrogen sulfide, then the hydrogen sulfide gas is contacted with liquid sulfur dioxide to yield solid sulfur and ice. The solid sulfur thus produced contains over 50 weight percent of the amorphous sulfur ,u and can be easily recovered from the sulfur dioxide an ice preparatory to forming a slurry suitable for shipping the sulfur. The preference for utilizing this method of preparing sulfur t stems from the ease with which the sulfur can be converted to hydrogen sulfide, the fact that other methods of producing sulfur ,u require inputs of large quantities of heat, and the fact that hydrogen sulfide is itself an abundant by-product of the oil and gas industry and thus may provide a significant source of sulfur which it is desirable to ship by the described method. Where crystalline sulfur is available and to be shipped, it can be converted to hydrogen sulfide by contacting the ele- 3 mental sulfur with hydrogen gas at temperatures less than 310 C. If the sulfur is available in the form of ores, such as metallic sulfides, these can be contacted with a suitable acid to form hydrogen sulfide The gas can prior to grinding and introduction into the pipeline charge.

The sulfur is moved through the pipeline as a slurry. To form the slurry, the sulfur, preferably including also be prepared by heating mixtures of sulfur, paraffin 5 at 1ea $t 1 Weight P and most Preferably at least hydrocarbons and asbestos fibers. In instances where a P of the ph h form of the m large supply of sour natural gas is at hand, this material is initially commin uted or subdivided to form relatively is sufficiently rich in H S that it can be passed directly PartleleS .whleh Preferably do not exceed lheh into the liquid sulfur dioxide to provide a substantial m diameter- It most preferred that the partlclts 3 quantity of solid sulfur. exceed inch in average diameter. Any suitable grinding The procedure of contacting the H 8 gas with the liquid eothmlhutloh Procedure be used to etteet the P sulfur dioxide can be carried out at a wide variety of t1e1eS1ZeIedhet1 )htemperatures and pressures, provided the S0 is retained I yp of hqhld earner employed 13 not paftleulafly in the liquid state and the H 5 in the gaseous state. It is erltleal, but should a hon-Solvent for the element preferred however, to operate at pressures of from about 15 Sulfur, of at least dissolve the Sulfur to no greater 15 to about 30 p.s.i.a. and at a temperature below about teht than 5 Percent by Welght- Th Slurry ferm'of trans- 10 C. The yield of sulfur u from the reaction decreases P has the advantage t perlhlttlng tWO mateflais t be as the temperature at which the reaction is carried out is moved thfehgh the P p slmultanjwusly e P decreased. On the other hand, it is preferred to maintain g deshahle use as the earner h h g a hqhld the temperature and pressure in the reaction zone at levels Whleh 13 pp In theleeale of the ol'lglhatloh such that the water produced by the reaction occurs as h Shlpmeht, t h 15 1h demand at the heshhahoh- This prevents hydration of the liquid 0 reduces Since petroleum derivatives are frequently available near corrosion problems, and simplifies the separation of the h deposltei pahtlchlarly 1n the Uhlted S t Preferred reaction products from the sulfur dioxide. In view of these Gamer matertats h h but are h hhhtett Such considerations bearing upon the temperature range empetrelehth dehved h e crude 011s, crude Oh cohdeh' pioyed, it is preferred to utilize a reaction Zone tempera sates, various crude oil distillates, kerosene and benzene. mm which is in the range of from about C. to The only significant limit on the viscosity of the slurry about at pressures of from about 15 to used for transporting the sulfur is that it be sufficiently about p.s.i.a. It should be pointed out, however, that low to he PhmPahle- It 15 preterahtyahoweveh to assure where immediate pipelining of the sulfur is in prospect, 30 ease of moYemeht through the Ptpehhet that the t it may be desirable to carry out the reaction at consider- Power reqhhemehts t pump the Slurry through the Ptpe' ably higher pressures, and in these cases the temperatures hhe hot exceed t' tunes t horsepower F F to used will be adjusted to maintain the S0 in the liquid move h t hqhtd Gamer through the Ptpehhe', phase and the H23 in the gaseous phase Details of the The invention can be better understood by referring to procedure for contacting the gaseous H 8 with liquid the tohowlhg examples Ottts ptachce' S0 are set fgrth I\iIri co-pending application for4 U.S. Example] Letters Patent er. 0. 422 257 filed Dec. 30 196 and assigned to the assignee of thishpplication. In laboratory tests? Sohd Sum}? prepared y h Upon completion of the reaction, little difliculty is t q hfarembefore tiescnbed was Slum-let. m experienced in separating the solid products, sulfur and vanous Gamer hqmqs h slumes were then placed m ice, from the liquid S0 and, if desired, the ice may then glass tf matnthmed at a.constant temperatum. of be melted and the solid sulfur easily separated from the fig g f i d as g tzi 2225 2 2: resulting water in which it is insoluble, and finally dried. tubes t tab i eratur; at about C After If it is desired to ship only the portion of the solid sulfur e 1 sulfu which had itated product which is in the amorphous allotropic form, and z i a collected rdried and g g I'Y g' ggfi fg tg g gi 2:; g hs g s In preparing the solid sulfur by the reaction of gaseous 1h ex S 3 H 8 with liquid S0 the S0 was maintained at a temfrom the crystalline sulfur by selective extraction of perature of between and In some of the latter material w1 th carbon disulfide in which the the ulfur tio ure hydrogen sulfide gas was emorphells sulthf 1S lhsohlble- In general, however, It utilized; in others, sour natural gas containing a high per- 15 Preferred Ilelthel' to dry Separate the Sulfur i centage of hydrogen sulfide gas was employed. In all TABLE I Tcmpera- S=Liquid Duration Plating Carrier Liquid Sulfur Source ture of Ratio, of Run, on Tube, Comments Slurry, C. gms./m1. hours grams of S Sour Condensate 1 Flowers of Sulfur 6 16,7

D01 H SSO Rcactiom. 6 0 Do do 6 o Kerosene.-. Flowers of Sulfur 24 35. 7

D 24 28. 0 Water wet before test.

22: CS; wet before test. 24 1 7 Aged in kerosene 24 hrs. before test. 24 4. 7 Hi0 washed to remove 24 16.3 SO in sulfur neutralized. 24 12. 5 Aged in C5 24 hours before test. 24 7. 5 Sulfur not dried prior to test. 24 13. 5 Sulfur dried prior to test. 2 52.5; Sulfur not dried prior to test. 88: 0 Kerosene wet before test. Bcnzerie Flowers of Sulfur 24 40.0

Do H SSO Rcaction 24 1. 5 Sulfur not dried prior to test. Do do 24 2.5 Sulfur dried prior to test. Do -do 24 2.3 Sulfur not dried prior to test.

1 The sour condensate carrier liquid had the following compositioncomponent and weight percent: Propane, 0.2; iso-butane, 1.0; normal bguiane, 2.8; iso-pentane, 3.6; normal pentane, 3.3; hexanes and heavier t In these runs the His was derived from sour natural gas which was passed directly into the liquid SOi.

cases, the solid sulfur resulting from the H S-SO reaction contained from 50 to 60 weight percent of the amorphous or sulfur ,u. allotropic form of the element.

For purposes of comparison, slurries of commercially available Flowers of Sulfur in the same carrier liquids were subjected to the same plating or precipitation tests. Flowers of Sulfur consists almost entirely of the crystalline form of the element and thus simulates closely the form in which elemental sulfur has heretofore been transported as a slurry through pipelines.

The results obtained in all runs are set forth in Table I.

The data set forth in Table I clearly indicate that the solid sulfur containing a high percentage of sulfur ,u. plates out to a much lesser extent than the crystalline Flowers of Sulfur. The data also indicates that some further reduction in precipitation occurs when the sulfur is moistened with water prior to formation of the hydrocarbon carrier slurries. In the case of the sulfur formed from the H S-SO reaction, some moisture formed in the reaction is occluded in the sulfur and unless it is removed by drying, remains therein as the slurry is formed. The mechanism by which the moisture further retards precipitation is not known.

Exalmple 2 A slurry comprising 50 parts by weight sulfur a and 40 parts by weight kerosene is pumped through an eight inch pipe-line over a distance of 150 miles using an 8 stage centrifugal pump driven by a 1,000 horsepower electric motor. Upon completion of the pipeline transport, the pipeline is thoroughly cleaned internally and then a second slurry containing 5 parts by weight of 'crystalline sulfur and 40 parts by Weight kerosene is pumped therethrough, using the same pump and at the same rate.

The total sulfur content of the slurries arriving at the pipeline destination is then recovered from the kerosene. By this method, it is determined by difference that about 2 weight percent of the sulfur ,u. is left in the pipeline as a result of plating and precipitation, whereas about 20 weight percent of the crystalline sulfur precipitates in the pipeline.

From the foregoing description of the invention, it will have become apparent that an improved method for transporting sulfur by pipeline is provided. Lower sulfur losses in the pipeline result from the use of the method, and in addition, pipeline maintenance is decreased.

Although certain specific embodiments of the invention have been described as exemplary of its practice, these examples are not intended to limit the invention in any way, or to constitute any definition of its true scope. Other process parameters and materials may be used in accordance with the broad principles outlined herein, and when so used, are deemed to be circumscribed by the spirit and scope of the invention except as necessarily limited by the appended claims or reasonable equivalents thereof.

What is claimed is:

1. A method of transporting sulfur comprising:

(a) forming a pumpable slurry of solid particles of sulfur, wherein an amount effective to reduce precipitation and adherence to the interior parts of a transporting vessel is in the sulfur ,u. amorphous allotropic form; and

(b) pumping said slurry through a pipeline.

2. A method of transporting sulfur comprising:

(a) converting an amount of the sulfur to the sulfur p. amorphous allotropic form; said amount being effective to reduce precipitation and adherence to the interior parts of a transporting vessel;

('b) comminuting the sulfur to provide solid particles thereof;

(c) forming a pumpable slurry of the solid particles of sulfur in a carrier liquid; and

(d) pumping the slurry through a pipeline to the location to which the sulfur is to be transported.

3. A method of transporting sulfur as defined in claim 2 wherein at least 50 weight percent of the sulfur to be transported is converted to the sulfur ,u amorphous allotropic form.

4. A method of transporting sulfur as defined in claim 2 wherein the average size of said particles does not exceed inch in diameter.

5. The method of transporting sulfur defined in claim 2 wherein said carrier liquid is selected from the group consisting of sour crude oil condensate, kerosene and benzene.

6. The method of transporting sulfur as defined in claim 2 wherein the amount of sulfur slurried with said carrier liquid imparts a viscosity to said slurry such that the horsepower requirement to pump said slurry through said pipeline does not exceed 4.8 times the horsepower requirement to pump said carrier liquid alone through said pipeline.

7. The method of transporting sulfur defined in claim 2 wherein said converted portion of the sulfur is converted y (a) converting a portion of the sulfur to hydrogen (b) contacting the hydrogen sulfide in a gaseous state with liquid sulfur dioxide; and

(c) recovering as a reaction product of said contact,

solid sulfur containing at least 50 weight percent sulfur ,u..

'8. The method of transporting sulfur defined in claim 7 wherein the hydrogen sulfide is contacted with the liquid sulfur dioxide at a temperature of from about -60 C to about -'10 C.

9. The method of transporting sulfur defined in claim 7 wherein sulfur s in said reaction product is recovered by selectively extracting the crystalline sulfur therefrom with carbon disulfide.

10. The method of transporting the sulfur content of sour natural gas from a source of the gas to a remote location comprising:

contacting the sour natural gas with liquid sulfur dioxide to yield water and solid sulfur with an amount of the sulfur in the sulfur a amorphous allotropic form; said amount being effective to reduce precipitation and adherence to the interior parts of a transporting vessel;

recovering the solid sulfur from the environment of said contact;

forming a pumpable slurry of the solid sulfur in a carrier liquid; and

pumping the slurry through a pipeline to the location to which the sulfur is to be transported.

References Cited UNITED STATES PATENTS 2,534,063 1'2/ 1950 Ross et a1. 23-225 2,798,772 7/ 1957' Redcay 23-229 X OSCAR R. VERTIZ, Primary Examiner. A. GRIEF, Assistant Examiner. 

1. A METHOD OF TRANSPORTING SULFUR COMPRISING: (A) FORMING A PUMPABLE SLURRY OF SOLID PARTICLES OF SULFUR, WHEREIN AN AMOUNT EFFECTIVE TO REDUCE PRECIPITATION AND ADHERENCE TO THE INTERIOR PARTS OF A TRANSPORTING VESSEL IS IN THE SULFUR U AMORPHOUS ALLOTROPIC FORM; AND (B) PUMPING SAID SLURRY THROUGH A PIPELINE. 